JPH05156393A - Member for electronic parts - Google Patents

Abstract

PURPOSE:To provide a member for electronic parts with excellent soldering property, soldering weather resistance and plating properties as well as mechanical strength and bonding properties to be required by constituting it of a compsn. contg. specified amounts of one or more kinds of Pb and In and the balance one kind among Cu, Fe and Al. CONSTITUTION:This member for electronic parts contains, by weight, 0.1 to 50% of one or more kinds of Pb, In and the balance one kind among Cu, Fe and Al. As for the content of Pb and/or In, in the case of <1%, it is insufficient for the improvement of its soldering weather resistance, and on the other hand, in the case of >50%, its strength deteriorates. In the case the balance is constituted of iron, Pb and In do not enter into solid soln., thus, they are separated into a Pb (In) phase and an Fe phase in the stock, and Pb and In phases form an eutectic structure with Sn or the like in solder to facilitate soldering. Next, in the case the balance is constituted of Al, it forms an eutectic structure with Pb or In and Sn in the solder to keep solid bonding. Moreover, in the case th content of Pb and In is increased on the surface part more than that on the inside of the member, the eutectic structure is made easy to form.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member for electronic parts, and more particularly as a material for consumer devices such as lead frames of semiconductor devices, carrier frames (TAB tapes), bonding wires / bumps, connectors, switches and the like. The present invention relates to a useful electronic component member.

[0002]

2. Description of the Related Art Consumer products such as transistors and ICs
Semiconductor devices such as (integrated circuits) and LSIs (large-scale integrated circuits) are required to have high output and multi-function, which are generally required for products, and to be mass-produced at low cost. ..

Therefore, a semiconductor device having a resin-sealed structure shown in FIG. 5 is known as a semiconductor device satisfying these requirements. That is, a pellet 22 which is a semiconductor chip is die-bonded (or mounted) on a die frame (or tab) 21, and a film-like electrode (chip electrode) of the pellet 22 and a lead frame 23 are connected by a lead wire 24. It Finally, these are molded with the resin 25 to complete the resin-sealed semiconductor device. At this time, the portion of the lead frame 23 inside the resin mold 25 is called an inner lead.

The lead frame 23 is required to have the following properties in relation to the above requirements. That is, the surface oxidation is small, the press punching property when punching by a press or etching using a ferric chloride solution, etc., the workability such as press bendability (ductility) and the etching property are good, Excellent high-temperature characteristics (eg mechanical strength at temperatures of 250 ° C. or higher), solderability (wetting with solder, solder plating),
Solder weather resistance, good plating property, etc.

Therefore, up to now, 42Ni--Fe alloy has been widely used as a lead frame material relatively satisfying the above properties.

On the other hand, even in consumer devices, LEDs (light emitting diodes) and the like using optical semiconductors often use Al alloys in order to improve the light reflectance. In this case, Si or Mg may be added to increase the strength. In addition, an Al clad may be used for a lead frame used for an LSI or an IC in order to improve the bonding property.

Further, for the lead wire, a Cu-based material having an appropriate strength for bending is used.

[0008]

However, considering the case of soldering the above materials, first, 42Ni-F is used.
The iron-based alloy of e cannot be soldered without a strong flux (solvent). For this reason, organic solvents (freon-cleaned) have been used. However, since these lead to environmental pollution, there is a demand for a lead frame material that can be soldered with a water-soluble flux.

On the other hand, Al-based materials cannot be directly soldered. Therefore, when the Al clad is applied, it is necessary to peel off the clad only in the portion to be soldered. In addition, when soldering directly to Al by the recent ultrasonic soldering method, Sn and Al in the solder react with each other to form a layer having no corrosion resistance at the interface.

In addition, although Cu-based materials can be soldered, a hard intermetallic compound such as Cu ₃ Sn or Cu ₆ Sn ₅ may be generated at the interface between the two materials and the solder may peel off (solder Weather resistance is poor).

As described above, conventionally, the electrical connection of electronic component members (lead frame, carrier frame (TAB tape), bonding wire / bump, connector, etc.) has not always been sufficient.

For example, the lead frame has insufficient soldering and solder plating properties, and the carrier frame has S.
n, Solder platability was insufficient, bonding wire bumps had insufficient plastic deformability, and connector switches had insufficient solderability and solder platability.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a member for electronic parts which is excellent in solderability, solder weather resistance, and plating property.

[0014]

In order to solve the above problems, the present invention contains 0.1 to 50% by weight of at least one of Pb and In, and the balance is substantially Cu,
Provided is a member for electronic parts made of any one of Fe and Al.

At least one of Pb and In is 0.1
The content of up to 50% by weight is insufficient to improve the solder wettability and the solder weather resistance if it is less than 0.1% by weight, and on the other hand, if it exceeds 50% by weight, the strength of the manufactured electronic component member decreases. This is because.

When the balance is iron, Pb and In do not form a solid solution with Fe, so that they are divided into Pb (In) phase and Fe phase in the material. Therefore, the Pb and In phases form a eutectic structure with Sn and In in the solder, which facilitates soldering. In the case of iron, the content of Pb and In is preferably 0.5
-30% by weight, more preferably 2-15% by weight.

By containing Pb and In, solderability, solder plating property, Sn plating property, Au, Ag plating property, plastic deformation and the like can be improved.

Surface treatment for facilitating soldering is carried out as necessary. When the added amount of Pb and In is small, the Fe phase is selectively etched to condense Pb and In on the surface to be soldered. The etching is preferably performed by dipping in an acid such as hydrochloric acid, sulfuric acid or hydrofluoric acid in a non-oxidizing atmosphere. Immersion in caustic soda is also effective.

As unavoidable impurities, Al, Ti, C,
O, Si, Mn, P, Zn, Ta, Nb, etc. are 5% by weight
Within the range, it is useful for improving the product strength, for example, the strength of the lead frame. Further, although Cr is solid-dissolved in the Fe phase to improve the corrosion resistance, it is preferable that the content of Cr is 3 to 10% by weight in order to exert a predetermined effect and not repel solder.

The manufacturing method may be a molten metal quenching method, or Fe, P
Alternatively, a flux that forms a solid solution with each element of b and In, for example, Ti, Si, and the like may be mixed, melted, and rolled. A molten metal quenching method that can reduce the difference in specific gravity is preferable. At this time, the melt quench rate is 100 ° C /
Cooling with twin rolls is suitable for obtaining a plate thickness of more than a second and with accuracy.

Next, when the balance is aluminum, Pb or In forms a eutectic structure with Sn in the solder to maintain a firm bond. However, if Pb and In are less than 0.1% by weight, they do not form a solid phase as a solid solution in the Al phase, and it becomes difficult to form a eutectic structure with solder. The desirable addition amount is 5 to 25% by weight.

The Pb and In phases have a solid solution width to some extent with the Al phase, but are phase-separated in the metal body. Figure 1
[Fig. 3] is a metallographic chart showing the state of phase separation. A
The crystal grain size of l-phase 1 is preferably JIS 0551 austenite grain size number 6 or more (because it is too coarse if it is less than 6). In the figure, reference numeral 2 is a Pb phase or an In phase. The crystal orientation need not be specified.

In addition to Al, Pb and In, Cu, Si, Zn, Mg, Ti, Fe and Ni can be applied to the metal body.
May be included. Si and Zn up to 5% by weight are effective in improving strength, and Cu and Ni up to 50% by weight are Al.
Since the intermetallic compound with Al is formed in the phase, the strength is most improved. Al, Cu and Fe form the base material. Especially C
u improves conductivity and Fe improves strength. Al improves connectivity and is suitable for applications such as LEDs because of improved reflectance.

FIG. 2 is a metallographic diagram when the solder 4 is joined to the metal element body (member for electronic parts) 3 composed of the Al phase 1 and Pb or In phase 2 of the present invention. A eutectic structure of Pb or In phase 2 and Sn5 is formed at the interface between the solder 4 and the solder 4. Reference numeral 6 indicates Pb in the solder 4. At this time, the Al phase 1 on the surface of the metal element body 3 is selectively etched with dilute hydrochloric acid or dilute hydrofluoric acid to enrich Pb and In (Pb, In).
In the -rich or In-rich) state, a eutectic structure is likely to be formed.

When wire-bonding to the Al-Pb, In metal element, the wires are Au, Cu, A.
Direct bonding is possible with any of the products manufactured by L. At this time, as shown in FIG. 3, the wire 7 contacts both the Al phase 1 and the Pb or In phase 2, but when the wire 7 is made of Au, both phases 1 and 2, Cu, and Al are made. In the case of (1), there is no problem because it is bonded to Al phase 1.

Finally, if the balance is a copper metal body, P
When b and In are added, the above-mentioned harmful intermetallic compound between Sn and Cu is less likely to be generated at the interface between the two at the time of solder dipping or burn-in after solder plating, and reliability for long-term use is increased. At this time, a preferable Pb content range is 2 to 20% by weight.

As unavoidable impurities, Zn,
S, P, O, C, N, Au, Sn, etc. are conceivable, but the properties are not affected if the amount is small.

[0028]

【Example】

<Examples 1 to 14> (Examples as lead frame) Components shown in Table 1 below (in the table, for example, Fe-5 of Example 1)
Pb means that Pb is 5% by weight and the balance is Fe. The same applies to the following examples and tables. The metal element bodies of Examples 1 to 14 having That is, the material is made by the twin roll method and the plate thickness is reduced to 1 mm. The cooling rate is 100 ° C./sec or more, after which cold rolling and annealing are repeated until the plate thickness reaches 0.25 mm. The metal phase is at least one phase containing Pb or In as a main component (up to 20% forms a solid solution when both Pb and In are contained, but if it is more than that, Pb and In are separated), and Al , Cu, Fe phases are separated. Solder plating or partial solder dip is applied to the outer layer surface. As evaluation, solder plating property,
For the Al material, which has solderability, strength (Vickers hardness), and bondability, the reflectance was also targeted. Examples 1 to 5 were manufactured by a melt quenching method, and Examples 6 were manufactured by a melting method. Further, the former was cold rolled, and the latter was hot rolled and cold rolled repeatedly to have a thickness of 0.25 mm. Finished in the plate. Then, the thin plate-shaped coil was punched into a lead frame having a predetermined shape.

Then, the Si semiconductor pellets are die-bonded and wire-bonded with a wire made of Au. Then, after electrically connecting the pellet and the lead frame, the pellet was protected with a mold resin, and cutting and bending were performed to complete an electronic component.

An outer lead of the lead frame of this electronic component (a portion of the lead frame exposed from the resin mold) was subjected to a soldering test. Solder is P
The b-Sn eutectic solder was soaked for 5 seconds at "260 ° C. The flux used was water-soluble.
%, The surface was considered good, and the surface less than that was considered poor. In addition, in Examples 2 and 6, the surface treatment shown in the remarks column of the table was performed, and in Example 6, solder was attached by plating.

On the other hand, as Comparative Example 1, the same experiment was conducted for a lead frame of 42Ni-Fe alloy.

[0032]

[Table 1]

As can be seen from Table 1, the lead frames of Examples 1 to 6 all showed good solder wettability,
This was in good contrast to the poor 42Ni-Fe alloy.

<Examples 7 to 11> The molten metal containing the components shown in Table 1 above was rapidly cooled with a twin roll drum (cooling rate of about 100 ° C / sec) to uniformly mix Al with Pb or In. We will make a 3mm thick plate. After this, further strain relief annealing is performed, and 0.25 mm is obtained by cold rolling.
I made a thick plate. Then, this plate material was press-molded to form a lead frame having inner leads and outer leads, and a resin-molded electronic component was manufactured in the same manner as in Examples 1 to 14.

After that, the outer leads were washed with dilute hydrofluoric acid, and Pb-Sn eutectic solder (so-called silver-containing solder) containing 5% by weight of Ag was used to complete the outer lead bonding at 260 ° C. At this time, a water-soluble flux was used for some of those having a small amount of Pb and In. On the other hand, Pb,
Lead frames of Comparative Examples 2 and 3 having In contents outside the range of 0.5 to 50 wt% were manufactured.

Table 2 shows the mechanical strength (Vickers hardness tester) of the lead frames of these Examples and Comparative Examples, and the bondability with the solder interface (“Good” was evaluated as “Good” by the same evaluation method as in Examples 1 to 6 above). "Poor" x) and bondability (peel tester) are shown together. In the table, "two phases" in the column of "structure" indicates that the phase is divided into Al phase and Pb, In phase, and "single phase" indicates that no phase other than the Al phase is recognized.

As can be seen from the above table, Examples 7-11
The lead frame of No. 3 showed good results in all of solderability, strength, and bondability. But P
Comparative Example 2 in which the content of b is insufficient has poor solderability, while I
Comparative Example 3 having too much n content is inferior in strength.

[0038]

[Table 2]

The Al-In melt of the components according to Examples 24, 25, and 26 in Table 2 above was placed in a tundish, and passed through a 50 μm hole provided at the bottom of this tundish, and onto the cooled rotating roll, Al-In. Injecting and quenching molten metal,
A wire in which Al-In was uniformly mixed was obtained (single roll method or twin roll method). The cooling temperature at this time is 150
C / sec. Thereafter, the wire was aged at 100 ° C. for 30 minutes, and the temperature was further lowered to room temperature. Then, this wire was wound on a roll to form a lead wire (bonding wire).

This lead wire was connected to the Al electrode of the semiconductor chip and the lead frame using an ultrasonic bonder. At this time, the stage on which the semiconductor chip is mounted is 20
Heated to 0 ° C. As a result, the bonding strength between the Al-In lead wire and the Al electrode of the semiconductor chip was 60 g /
Good with wires and no electrode damage. In addition, each Al-
The bonding strength between the In lead wire and the lead frame was about the same.

Thereafter, the bonded semiconductor chip, Al-I
After coating and curing the n lead wire and the lead frame with an epoxy resin, the outer lead of the lead frame was cut and bent to complete a semiconductor device (electronic component). For this semiconductor device, a temperature cycle test (-55 ° C. × 30 minutes → 25 ° C. × 20 minutes → 150 ° C. × 30) for examining resistance to thermal stress
Even if the test of giving a cycle of minute temperature change) was repeated 200 times, the wire was not broken.

Then, a lead wire having the components of Example 27 shown in Table 3 above was obtained in the same manner as in Examples 24, 25 and 26, and the Al--In lead wire shown in FIG. 4 was used. The semiconductor device 10 was manufactured. That is, after ball-bonding the Al-In lead wire to the electrode film of the semiconductor chip 12, the wire was cut while leaving the ball to form the ball-type bump 13. At this time, no damage to the electrode film was observed. <Examples 15 to 23> (Examples as carrier frame) Next, TAB (Tape Automated) made of Cu-3In.
Inner lead 1 of carrier frame 14 for Bonding)
4a and the ball type bump 13 were joined. At the time of this bonding, the Sn plating on the surface of the inner lead 14a formed a eutectic structure with Pb of the ball type bump 13. As a result, the bonding strength between the inner lead 14a and the ball-shaped bump 13 is
A good value of 70 g / lead was shown. The carrier frame is made by attaching an insulating tape (polyimide) with an adhesive and etching a predetermined pattern. The method of making rolled material is the same as that of lead frame, and the plate thickness is 0.
01 mm and the metal phase is the same.

[0043]

[Table 3]

Further, after the semiconductor chip 12, the ball type bumps 13 and the inner leads 14a were sealed with the potting resin 15, the same temperature cycle test as in the previous embodiment was conducted, but the operation of the semiconductor device 10 was not abnormal. I couldn't see it.

The evaluation is Sn or solder plating property, adhesiveness with polyimide, etching property, strength and the like. Example 2
In 1 there was no electrolytic corrosion (Comparative Example 5 had electrolytic corrosion).

<Examples 28 to 33> (Examples of connectors and switches) Connectors and switches were manufactured in the same manner as in the above examples.

[0047]

[Table 4]

In the switch and the connector, the slidability at the contact is required. As shown in Table 4 above, in addition to the plating property, solderability, and strength, the slidability was also an evaluation item.

According to the present embodiment, improvement in soldering, solder plating property and strength, slidability, etc. can be confirmed.

[0050]

As described above, the electronic component member of the present invention has excellent solderability and solder weather resistance, and also achieves the mechanical strength and bonding property required for electronic components.
Therefore, it is extremely useful as a material for electronic parts.

[Brief description of drawings]

FIG. 1 is a metallographic view of a metal element body composed of components according to the present invention.

FIG. 2 is a metallographic diagram when the metal element body of FIG. 1 is soldered.

FIG. 3 is a metallographic diagram when a wire is bonded to the metal element body of FIG.

FIG. 4 is a sectional view of a semiconductor device formed by bump connection of lead wires according to an embodiment of the present invention.

FIG. 5 is a sectional view of a resin-sealed semiconductor device.

[Explanation of symbols]

 1 Al phase 2 Pb, In phase 4 Solder 5 Sn phase 6 Pb phase 7 Lead wire

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoko Yokouchi 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Inside the Toshiba Research Institute Ltd. (72) Inventor Mitsuhiro Tomita Komukai-Toshiba, Kawasaki-shi, Kanagawa No. 1 Incorporated company Toshiba Research Institute (72) Inventor Miki Honma Komukai Toshiba-cho, Kouki-ku, Kawasaki-shi, Kanagawa No. 1 Incorporated Toshiba Research Institute (72) Inventor Masahiko Yoshiki Ko, Kawasaki-shi, Kanagawa Muko Toshiba Town No. 1 Incorporated company Toshiba Research Institute (72) Inventor Tatsuya Hatanaka Komukai-ku Kawasaki City Kanagawa Prefecture Komu Toshiba No. 1 Toshiba Corporation Research Institute (72) Inventor Takahashi Futoshi Kawasaki Kanagawa Komukai-shi Toshiba-cho 1-share company Toshiba Research Institute Ltd. (72) Inventor Hideki Matsunaga Komu-shi Toshiba-cho 1-shi, Kawasaki-shi, Kanagawa Stock-owner Toshiba Corporation The laboratory

Claims (2)

[Claims] 1. At least one of Pb and In.
A member for electronic parts, containing 1 to 50% by weight, and the balance substantially consisting of any one of Cu, Fe and Al. 2. The member for electronic parts according to claim 1, wherein the contents of Pb and In are higher in the surface portion than in the inside of the member.